THE ROLE OF CARDIOLIPIN IN THE TCA CYCLE: IMPLICATIONS FOR BARTH SYNDROME

项目摘要 心磷脂(CL)，线粒体膜的标志性脂类，对最佳 线粒体功能。CL的摄动突显了CL的重要性 CL重塑酶Tafazzin(Tafazzin)突变导致的代谢导致生命- 具有威胁性的遗传性疾病，巴特综合征(BTHS)。而扩张型的临床表型 心肌病和骨骼肌病指向线粒体生物能量缺陷，这种紊乱 其特征还包括广泛的代谢失调，包括氨基酸水平异常 和TCA循环相关的代谢物。这些研究表明，CL起着重要的作用 不仅在氧化磷酸化中，而且在中间代谢中。分子 CL缺乏与BTHS的这些代谢变化和病理机制有关 都是未知的。 我们正在使用两个强大的模型研究CL在新陈代谢中的作用。酵母菌CL 我们以前产生的突变crd1D是一个成熟的CL缺乏模型。更多 最近，我们在小鼠成肌细胞C2C12细胞系中构建了Taz基因敲除突变体TAZ-KO。 Taz-KO细胞表现出BTHS和BTHS特有的生化和线粒体表型 贡献出一种新的紊乱模式。实施这两种模型后，我们确定CL 调节在三氯乙酸循环中汇聚的两条途径--乙酰-辅酶A合成和铁-S 生物发生学。基于这些发现，将使用遗传、生化和新陈代谢方法 为了检验中央假设，即作为结果，三氯乙酸循环的最佳活动需要CL 它在调节乙酰辅酶A的合成和铁-S辅因子的生物发生中的双重作用。目标1将 明确CL通过增加乙酰辅酶A的活性来调节乙酰辅酶A合成的机制 丙酮酸脱氢酶。目标2将描述拯救三氯乙烷循环的逆流机制 不足之处。目标3建议定义CL在yfh1/frataxin成熟过程中的作用，yfh1/frataxin是一种重要的 铁-S机械的部件。 三氯乙酸循环是碳代谢的重要代谢途径。这个 目前的研究是由一个新的假说推动的，该假说确定了CL在调节TCA中的作用 周而复始。阐明这种调节作用背后的机制将建立一种新的范式 用于三氯乙烷循环控制。这一结果可能会为BTHS和其他疾病提供潜在的新治疗方法 线粒体心肌病。

Project Summary Cardiolipin (CL), the signature lipid of the mitochondrial membrane, is crucial for optimal mitochondrial function. The importance of CL is underscored by the fact that perturbation of CL metabolism due to mutation of the CL remodeling enzyme tafazzin (Taz) leads to the life- threatening genetic disorder, Barth syndrome (BTHS). While the clinical phenotypes of dilated cardiomyopathy and skeletal myopathy point to mitochondrial bioenergetic defects, the disorder is also characterized by broad metabolic dysregulation, including abnormal levels of amino acids and TCA cycle-associated metabolites. These studies suggest that CL plays an important role not only in oxidative phosphorylation but also in intermediary metabolism. The molecular mechanisms linking CL deficiency to these metabolic changes and to the pathologies in BTHS are unknown. We are investigating the role of CL in metabolism using two powerful models. The yeast CL mutant, crd1D, which we generated previously is a well-established model of CL deficiency. More recently, we constructed a Taz knockout mutant, TAZ-KO, in the mouse myoblast C2C12 cell line. TAZ-KO cells exhibit the characteristic biochemical and mitochondrial phenotypes of BTHS and contribute a new model of the disorder. Implementing both models, we have determined that CL regulates two pathways that converge on the TCA cycle - acetyl-CoA synthesis and Fe-S biogenesis. Based on these findings, will use genetic, biochemical, and metabolomic approaches to test the central hypothesis that CL is required for optimal activity of the TCA cycle as a result of its dual role in regulating synthesis of acetyl-CoA and biogenesis of Fe-S cofactors. Aim 1 will define the mechanism whereby CL regulates acetyl-CoA synthesis by increasing the activity of pyruvate dehydrogenase. Aim 2 will characterize anaplerotic mechanisms that rescue TCA cycle deficiencies. Aim 3 proposes to define the role of CL in maturation of yfh1/frataxin, an essential component of the Fe-S machinery. The TCA cycle is a fundamentally important metabolic pathway of carbon metabolism. The current study is driven by a novel hypothesis that identifies a role for CL in regulating the TCA cycle. Elucidating the mechanisms underlying this regulatory role will establish a new paradigm for TCA cycle control. The results may suggest potential new treatments for BTHS and other mitochondrial cardiomyopathies.